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      09-05-2018, 12:08 AM   #1
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Drives: E90 M3
Join Date: Jan 2016
Location: Sydney

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Throttle Actuator Circuit Fix (Possibly)

Okay here goes. After months of procrastination, I've finally got my arse off to write this fix for these morbidly expensive actuator units. Got most of my info to start off from here, hence I'd thought it'll be fair for me to share it since I'm not planning to capitalize on the information. Credits to the existing threads for proper disassembles and preliminary troubleshooting.

To take the damn things off, refer to

As for the circuit fix refer to this thread

The critical point would be to replace the mosfets with one which performs better than the HUFA76429D3ST_F085T-ND which is mentioned in the thread above. I'm using AUIRFR2905Z on both actuators, 5 per actuator.

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The parameter to look out for (besides the usual package size, voltage rating, current rating, vgs threshold voltage etc) would be the Reverse Recovered Charge of the Mosfet's body diode. And yes, this FET is automotive qualified as per AEC-Q101 as well.

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The whole issue with people replacing them mosfets and having only some slight chance of rectifying the actuator's circuit issue would be the replacement mostet's revese recovery response isn't acting fast enough to prevent the backlash from the DC motor of the throttle actuator. This in turn causes the throttle actuators jerk on the de-energising phase of the actuator which would cause the self test to fail on startup. From my tests any mosfet with reverse recovery QRR of less than 50nC works fine with our modules. I have only ever tested with 6 units of throttle actuators, 2 of them from my own car so do take note of that.

I've used a pair of the fixed unit on my e90 for about a year now without any issues whatsoever. Swapped out the worned oem gears with i6 automotive replacement gears. Usual disclaimer, you're going to have to do this fix on your own risk yada yada yada. Hope this will be of some help to another owner who isn't prepared to fork out thousands for a replacement unit. The END

Last edited by pubo; 09-05-2018 at 12:20 AM..
Appreciate 1

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